A magnetic memory cell or device stores information by changing electrical resistance of a magnetic tunnel junction (MTJ) element. The MTJ element typically includes a thin insulating tunnel barrier layer sandwiched between a fixed ferromagnetic layer and a free ferromagnetic layer, forming a magnetic tunnel junction. The resistance state of the MTJ element changes corresponding to that of the magnetic orientation of the free layer relating to the fixed layer, which may be in either a parallel (P) state or an anti-parallel (AP) state. The corresponding electrical resistance between the free layer and the fixed layer in P state is denoted as RP while the corresponding electrical resistance between the free layer and the fixed layer in AP state is denoted as RAP. The performance of an MTJ element is usually characterized by its tunneling magnetoresistance (TMR), which may be calculated using the formula given by (RAP−RP)/RP. For example, a larger TMR ratio facilitates read operations in a magnetic memory cell. Thus, an enhanced TMR is necessary for realizing next-generation magnetic memory cells.
It is desirable to provide a reliable memory device with an enhanced TMR ratio and a method for forming a reliable memory device which eliminates the high temperature concern for the MTJ element. Furthermore, it is also desirable that the process is cost effective and is compatible with logic processing.